CN104850165B - Control circuit, control method and its electromagnetic oven for electromagnetic oven - Google Patents
Control circuit, control method and its electromagnetic oven for electromagnetic oven Download PDFInfo
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- CN104850165B CN104850165B CN201510114971.3A CN201510114971A CN104850165B CN 104850165 B CN104850165 B CN 104850165B CN 201510114971 A CN201510114971 A CN 201510114971A CN 104850165 B CN104850165 B CN 104850165B
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Abstract
There is provided a kind of control circuit for electromagnetic oven, control method and its electromagnetic oven.The control circuit includes：Digital control part, according to the power that actually enters of the rectified corresponding first voltage signal of input voltage and second voltage signal of change electromagnetic oven corresponding with electromagnetic oven main circuit current received from simulation control part with electromagnetic oven, and this is actually entered into power relatively change the first reference voltage compared with user's setting power；Simulation control part, is controlled based on the first reference voltage and second voltage signal to major loop switch.The present invention is controlled by the way of analog control circuit and digital control circuit are combined to electromagnetic oven switch, and induction cooker system can be protected in time, greatly improves the security of induction cooker system；Meanwhile, the voltage to the switching device of electromagnetic oven is monitored using dynamic voltage threshold, can provide the overcurrent protection under all power and phase condition to induction cooker system.
Description
Technical field
This invention relates generally to household appliance technical field, it is more particularly related to a kind of control for electromagnetic oven
Circuit processed, control method and its electromagnetic oven.
Background technology
Electromagnetic oven is using magnetic field induction vortex principle, using high frequency electric by loop coil, so as to produce countless envelopes
Magnetic field force is closed, makes pot voluntarily fast heating in itself, so that food in heating kettle.When high frequency electric is passed through in coil, coil
Surrounding produces high-frequency alternating magnetic field.The magnetic line of force produced in high-frequency alternating magnetic field passes through permeability magnetic material (such as：Iron pot) bottom
Portion, makes iron pot bottom produce countless small vortex, so that the bottom of a pan discharges rapidly substantial amounts of heat, reaches heating purpose.Electromagnetism
The operating diagram of stove is as shown in Figure 1.
Fig. 2 is the schematic diagram of the major loop of electromagnetic oven work in the prior art, by full-wave rectification bridge, LC wave filters, electromagnetism
Coil MC, capacitor C0 are constituted with switch W.Here, the switch W is an insulated gate bipolar transistor IGBT.
Full-wave rectification bridge carries out full-wave rectification and obtains unidirectional Rectified alternating current to the alternating current AC IN being input into, and by by
The LC wave filters that inductance L and capacitor C in series are constituted enter to the unidirectional Rectified alternating current obtained after rectifier bridge carries out rectification
Row LC is filtered, so as to the point being connected with capacitor C in inductance L forms sinusoidal half-wave voltage Vin.By magnet coil MC and electric capacity
One end of the device C0 resonance circuits for constituting in parallel is connected to the point that inductance L is connected with capacitor C, and the other end is connected with switch W.
Switch W is constantly turned on and disconnected, input voltage V during conductinginMagnet coil two ends are added in, magnet coil MC and with it simultaneously is flowed through
The forward current of the capacitor C0 of connection increases, and magnet coil MC forms high-frequency resonant, electromagnetism with capacitor C0 in parallel during disconnection
Voltage reversal on coil MC, the electric current for flowing through magnet coil MC reduces, and the variable-current for flowing through magnet coil MC forms high frequency
Alternating magnetic field.The alternate magnetic force line that alternating magnetic field is produced passes through pan, and vortex is formed in iron pot body, pot is generated heat.Therefore,
Electromagnetic oven is to adjust power by the break-make of controlling switch W.
Traditional electromagnetic oven is all, using MCU controls, when power is more than certain predetermined value (such as 1000W), to take tune
The control mode of section ON time Ton, the excursion of Ton is controlled by micro-control unit (MCU), each Ton time correspondence one
Individual power；And when power is less than the predetermined value, control signal as shown in figure 3, ON time Ton is fixed on certain fixed value,
The time T1 and idle time T2 of switch W work is adjusted by MCU calculating power to be set to adjust to arrive power output
Value.
So, the traditional electromagnetic oven working condition when setting power is smaller is discontinuous, and water or food in pot are being opened
Close and fluidized state is in the time T1 of W work, can lower the temperature in the idle time T2 of switch W and lead to not continuous boiling
Rise.Such working method essentially cannot really realize low power working condition, and can be than continuously boiling
State needs the time that food is cooked longer, also more power-consuming.
The working condition to Fig. 2 is analyzed below, understands this frameworks of Fig. 2 are how to produce alternating magnetic field.
When switching W and closing, the ON time section of configuration switch W is Ton, after rectification half-wave voltage by magnet coil and
The switch of closure forms loop, and magnet coil MC is a linear inductance, and the electric current for flowing through magnet coil MC continues to increase.
Generally, due to the ON time Ton for switching W is smaller, therefore flows through the electric current of magnet coil MC and be approximately line
Property increase,
L·ΔiL=Vinputsinθ·Ton (1)
In formula (1), the electric current by magnet coil MC is Δ iL, θ is the phase angle of AC-input voltage Vin,
The crest of Vinput input voltage vins.Because input voltage is a sine wave shaped voltage, Vinputsin θ are out of phase angle
Under input voltage value.
Can be obtained by formula (1),
In addition, the turn-off time section of configuration switch W is Toff, after switch W disconnects, the energy in magnet coil MC is stored
The resonant capacitor C0 of parallel connection is transferred to, LC resonant tanks are formed.
Resonant frequency is：
Wherein, L is the inductance value of magnet coil MC, and C is the capacitance of the resonant capacitor C0 in parallel with magnet coil.
After energy of the storage in magnet coil MC is transferred completely on capacitor C0, capacitor C0 voltage highests, this
When be added in switch W on voltage reach resonance crest.
Formula (2) is substituted into formula (3), can be obtained：
Therefore, the crest V of resonance potential on W is switchedPEAKAlso sinusoidal variations are rendered as AC-input voltage.Work as electricity
In maximum, the ON time Ton for switching W also reaches maximum to the power setting of magnetic stove, because AC-input voltage is unstable, tool
Have certain fluctuation range for 176V~264V, if input voltage is high pressure 264V, the crest of resonance can close to 1200V, or even
The pressure voltage of switch W is reached, W is so switched and is possible to meeting excessive pressure damages.
When resonance is in crest, switch W may be caused to damage；Equally, when resonance is in trough, it is also possible to right
Switch W has undesirable effect.
When the energy on capacitor C0 is transferred completely on inductance the electric current for forming negative sense, energy all transfers again of inductance
Reverse voltage is formed on to capacitor C0, as shown in figure 5, the voltage on switch W is up to resonance trough, now：
VVALLEY=2Vinputsinθ-VPEAK (5)
Formula (4) is substituted into formula (5), can be obtained：
Wherein, VVALLEYIt is the peak voltage of resonance.From above-mentioned formula (6), on switch the peak voltage of resonance also and
AC-input voltage is equally rendered as sinusoidal variations.When the power setting of electromagnetic oven is in minimum, the ON time Ton of switch
It is most short；There is certain fluctuation range because AC-input voltage is unstable in 176V~264V, if input voltage is high pressure 264V,
The peak voltage of resonance can exceed 100V even more highs, if now conducting switch W, switch W can be damaged because being lost excessive
It is bad.
Therefore, if the resonance potential on switch W is controlled, including peak voltage and peak voltage, it will carry
The service life of height switch W, security when enhancing electromagnetic oven is used.
Analysis above is carried out under conditions of impedance loop is approximately 0, when there is electromagnetic oven to load access, impedance loop meeting
Increase, but analysis method is constant.
Fig. 4 represents the operation principle of resonance crest in the prior art using micro-control unit MCU controlling switches W.Due to
MCU is unable to the resonance crest that monitor in real time switchs W, and can just be subtracted by program when only the voltage on W is switched exceedes pressure point
The ON time in small next cycle, will the ON time in next cycle be adjusted to Ton- Δs T, this control mode cannot be from root
Overvoltage is avoided on this, and it is digital control due to using, and the change of Ton is discontinuous, can bring loop unstable in overvoltage
It is fixed.
In the case of high pressure underloading, because Ton reduces, the energy stored in inductance reduces same electromagnetic oven, so
Resonance peak voltage can be higher than predetermined voltage (for example, 50V), in some instances it may even be possible to more than 150V.Therefore, it is controlled using MCU
Method real-time detection and cannot control resonance peak voltage, when trough conducting voltage is higher, the unlatching of switch W during due to conducting
Peak current is very big, it is possible to damage switch W.
Fig. 5 is voltage waveform when there is surge in electromagnetic oven work, input voltage VinVoltage is leapt high, and is added in electromagnetic wire
Voltage on circle inductance is raised, and is increased by the slope Iw of the electric current of inductance, because the after reaction of Digital Circuit Control, conducting
Time TonWill not change in real time.Because current slope increases, if ON time TonIt is constant, then TonAt the end of, electricity
Stream IwCrest IpkTo be dramatically increased than a upper cycle, according toNow switch the voltage V on WWWill increase,
If VWPressure-resistant more than switch W, switch W will be demolished, and such case can not keep away when input voltage vin occurs surge
Exempt from；Above-mentioned calculating VWFormula in, VWTo switch the collector voltage crest of W, IpkTo flow through the colelctor electrode-emitter stage of switch W
CE electric current crests, L is electromagnetic stove coil inductance, and C is the capacitance of the capacitor being connected in parallel on electromagnetic oven inductance.Even if MCU leads to
Cross applied input voltage circuit for detecting and detect voltage and there occurs surge, but MCU is by computing, it is most fast to judge to need protection switch
The operation time of W is 1.3us, therefore the instruction of disconnection switch W sends the minimum delay with 1.3us, so using microcontroller
Unit MCU come to switch W carry out the bottleneck that overcurrent protection is electromagnetic oven security.
In addition, using the loop that MCU is controlled effective control cannot be carried out to the resonance crest of IGBT and resonance peak voltage
System.The pressure-resistant of the switch W (such as insulated gate bipolar transistor IGBT) used in electromagnetic oven for example can reach about 1200V, but
It is that the resonance wave summit that W is switched under the condition of work of input peak power (such as 2000W) exceedes pressure voltage, so needing
The additional resonance crest that will be switched of intervening is controlled within pressure voltage.
The drawbacks of being controlled to solve MCU described above, introduces simulation and is combined with digital control in the present invention
Mode.
The content of the invention
Exemplary embodiment of the invention, current foldback circuit of the invention is controlled by using analog circuit, right
Induction cooker system carries out timely overcurrent protection, greatly improves the security of induction cooker system；Meanwhile, to the derailing switch of electromagnetic oven
The voltage of part, is monitored using dynamic voltage threshold, and induction cooker system can be provided under all power and phase condition
Overcurrent protection.
According to an aspect of the present invention, there is provided a kind of control circuit for electromagnetic oven, including：Digital control part,
According to the corresponding first voltage signal of the rectified input voltage that is received from simulation control part with electromagnetic oven and with electricity
Magnetic stove main circuit current corresponding second voltage signal of change electromagnetic oven actually enters power, and actually entering electromagnetic oven
The power that power sets with user is compared to change the first reference voltage with so that electromagnetic oven actually enters power and sets
The difference for determining power is sufficiently small, and first reference voltage is input into simulation control part；Simulation control part, based on from number
First reference voltage and second voltage signal corresponding with electromagnetic oven main circuit current of word control section input are to electromagnetic oven
Major loop switch is controlled.
According to another aspect of the present invention, the analog control circuit may include：First control unit, will be with the first reference
The corresponding electric current of voltage difference between the voltage of voltage and second voltage signal is integrated acquisition tertiary voltage signal, and will make
For the voltage of the 4th voltage signal of ramp signal is compared to export the first control signal with the voltage of tertiary voltage signal；
Second control unit, voltage and the first threshold electricity of the 6th voltage signal based on the voltage change by the 5th voltage signal is reflected
Pressure carries out result of the comparison and the comparative result of first voltage signal and the 5th voltage signal is exported into the second control signal；Patrol
Control unit is collected, export the 3rd control signal based on the first control signal and the second control signal switchs with to electromagnetic oven major loop
It is controlled, wherein, the 5th voltage signal is corresponding to the voltage being applied on electromagnetic oven major loop switch.
According to another aspect of the present invention, first control unit may include：Resonance crest controls circuit, to electromagnetic oven
The resonance peak voltage of major loop switch is sampled, and the resonance peak voltage generation first obtained using sampling compensates electric current,
First control unit is added using electricity by the way that resonance crest to be controlled the first compensation electric current of circuit evolving with constant current
Container is generated as the 4th voltage signal of ramp signal.
According to another aspect of the present invention, first control unit may also include：Resonance trough controls circuit, to electromagnetism
The resonance peak voltage of stove major loop switch is sampled, resonance peak voltage generation the second compensation electricity obtained using sampling
Stream, wherein, first control unit controls the second of circuit evolving to compensate electric current phase by by constant current and resonance trough
Subtract the 4th voltage signal by the use of capacitor generation as ramp signal.
According to another aspect of the present invention, in resonance crest control circuit, be able to will be sampled by a RC integrating circuit
The normal phase input end in the resonance crest control source first voltage control electric current source for obtaining, and the second reference voltage is input into first
The inverting input of VCCS is generating the first compensation electric current.
According to another aspect of the present invention, in resonance trough control circuit, be able to will be sampled by the 2nd RC integrating circuit
The normal phase input end in the resonance peak voltage input second voltage control electric current source for obtaining, and the 3rd reference voltage is input into second
The inverting input of VCCS is generating the second compensation electric current.
According to another aspect of the present invention, in resonance crest controls circuit and resonance wave paddy control circuit, can be sharp respectively
With voltage follower circuit by the control source that obtains to a RC integrating circuit and the 2nd RC integrating circuit of sampling.
According to another aspect of the present invention, in resonance crest control circuit, the resonance peak voltage that sampling can be obtained
The first pulse signal relatively is generated compared with the 4th reference voltage, first voltage signal is adopted using the first pulse signal
Sample, and the first voltage signal that first voltage signal and sampling are obtained is separately input to the positive in tertiary voltage control electric current source
Input and inverting input are generating the first compensation electric current.
According to another aspect of the present invention, in resonance trough control circuit, the resonance peak voltage that sampling can be obtained
The second pulse signal relatively is generated compared with the 5th reference voltage, first voltage signal is adopted using the second pulse signal
Sample, and the first voltage signal that first voltage signal and sampling are obtained is separately input to the positive of the 4th VCCS
Input and inverting input are generating the second compensation electric current.
According to another aspect of the present invention, the logic control element can be rest-set flip-flop, and the first control signal is input to
The reset terminal of rest-set flip-flop, and the second control signal is input to the set end of rest-set flip-flop, when the first control signal is high level
When, the 3rd control signal from logic control element output is low level, and electromagnetic oven major loop is switched off；When the second control letter
Number for high level when, from logic control element output the 3rd control signal be high level, electromagnetic oven major loop switch conduction.
According to another aspect of the present invention, the analog control circuit may also include：3rd control unit, for producing guarantor
Shield control signal, the 3rd control unit includes surge protection circuit, and the surge protection circuit includes：Sample circuit, it is right
Second voltage signal is sampled and sampled second voltage signal is exported as the first output voltage signal；Differential amplification
Circuit, obtains voltage corresponding with the voltage difference between second voltage signal and the first output voltage signal；First comparator, will
The voltage is compared with second threshold voltage to export the 4th control signal as protection control signal, wherein, by the 4th
The voltage of voltage signal and the voltage of tertiary voltage signal are compared the result of acquisition and protection control signal carry out logic or
The first control signal is obtained after computing；Wherein, the cycle of the sampled signal that sample circuit is sampled to second voltage signal
Cycle phase with control electromagnetic oven major loop switch conduction and the 3rd control signal for disconnecting is same, and for second voltage signal
Peak voltage sampled.
According to another aspect of the present invention, sample circuit may include voltage follower, first being made up of operational amplifier
Switch and the first capacitor, the output end of the voltage follower are connected by first switch with the first capacitor, the first capacitor
Other end ground connection, the voltage signal on the first capacitor is input to differential amplifier circuit as the first output voltage signal；The
Two voltage signals are input into the normal phase input end of the operational amplifier.
According to another aspect of the present invention, the 3rd control unit may also include the overvoltage protection electricity of first voltage signal
The overvoltage crowbar of the switching voltage that road, the current foldback circuit of electromagnetic oven main circuit current, electromagnetic oven major loop are switched
At least one of protection circuit, wherein, the overvoltage crowbar of the first voltage signal by by first voltage signal with
First predetermined voltage compares and realizes, the current foldback circuit of the electromagnetic oven main circuit current with electromagnetic oven master by that will return
Electric current corresponding voltage in road realizes that the overvoltage crowbar of the switching voltage is by by instead compared with the second predetermined voltage
The voltage reflected on electromagnetic oven major loop switch is realized compared with the 3rd predetermined voltage, by being included in the 3rd control unit
The output of protection circuit carry out obtaining protection control signal after logic or computing.
According to another aspect of the present invention, second control unit may include the second capacitor and first resistor device, institute
State at the node that the second capacitor is connected with first resistor device produce the 6th voltage signal be input into the second comparator with
First threshold voltage is compared, wherein, when the voltage of the 6th voltage signal is less than first threshold voltage and first voltage letter
The second control signal for exporting is high level during number more than five voltage signals.
A kind of electromagnetic oven including control circuit as described above.
According to another aspect of the present invention, there is provided a kind of control method for electromagnetic oven, including：According to electromagnetic oven
The rectified corresponding first voltage signal of input voltage and second voltage signal corresponding with electromagnetic oven main circuit current
Calculate electromagnetic oven actually enters power, and the power that power sets with user that actually enters of electromagnetic oven is compared to change
Become the first reference voltage with so that electromagnetic oven to actually enter power sufficiently small with the difference of setting power；Based on first with reference to electricity
Pressure and second voltage signal are controlled to electromagnetic oven major loop switch.
According to another aspect of the present invention, the first reference voltage and the second voltage signal of being based on is returned to electromagnetic oven master
The step of way switch is controlled may include：By with the voltage difference phase between the voltage of the first reference voltage and second voltage signal
The electric current answered is integrated acquisition tertiary voltage signal, and will be electric as the voltage of the 4th voltage signal of ramp signal and the 3rd
The voltage of signal is pressed to be compared to export the first control signal；Based on the voltage change by the 5th voltage signal is reflected the 6th
Result that the voltage of voltage signal is compared with first threshold voltage and by first voltage signal and the 5th voltage signal
Comparative result exports the second control signal；And based on the first control signal and the second control signal export the 3rd control signal with
To electromagnetic oven major loop switch be controlled, wherein, the 5th voltage signal and be applied to electromagnetic oven major loop switch on voltage
Accordingly.
According to another aspect of the present invention, the resonance peak voltage of electromagnetic oven major loop switch can be sampled, is utilized
The resonance peak voltage generation first that sampling is obtained compensates electric current, is added with constant current using electricity by by the first compensation electric current
Container is generated as the 4th voltage signal of ramp signal.
According to another aspect of the present invention, the resonance peak voltage of electromagnetic oven major loop switch can be sampled, is utilized
The resonance peak voltage generation second that sampling is obtained compensates electric current, and electricity is utilized by by constant current and the second compensation current subtraction
Container is generated as the 4th voltage signal of ramp signal.
According to another aspect of the present invention, the resonance crest control source that can be obtained sampling by a RC integrating circuit
The normal phase input end in first voltage control electric current source, and the second reference voltage is input into the anti-phase defeated of first voltage control electric current source
Enter end to generate the first compensation electric current.
According to another aspect of the present invention, the resonance peak voltage that can be obtained sampling by the 2nd RC integrating circuit is input into
The normal phase input end in second voltage control electric current source, and the 3rd reference voltage is input into the anti-phase defeated of second voltage control electric current source
Enter end to generate the second compensation electric current.
According to another aspect of the present invention, the resonance peak voltage that sampling is obtained can relatively be come compared with the 4th reference voltage
The first pulse signal is generated, first voltage signal is sampled using the first pulse signal, and by first voltage signal and adopted
The first voltage signal that sample is obtained is separately input to the normal phase input end and inverting input in tertiary voltage control electric current source with life
Into the first compensation electric current.
According to another aspect of the present invention, the resonance peak voltage that sampling is obtained can relatively be come compared with the 5th reference voltage
The second pulse signal is generated, first voltage signal is sampled using the second pulse signal, and by first voltage signal and adopted
The first voltage signal that sample is obtained is separately input to the normal phase input end and inverting input of the 4th VCCS with life
Into the second compensation electric current.
According to another aspect of the present invention, when the first control signal is high level, the 3rd control signal is low level, electricity
Magnetic stove major loop is switched off；When the second control signal is high level, the 3rd control signal is high level, electromagnetic oven major loop
Switch conduction.
According to another aspect of the present invention, methods described may also include：Second voltage signal is sampled and will be through adopting
The second voltage signal of sample is exported as the first output voltage signal；Obtain and second voltage signal and the first output voltage signal
Between the corresponding voltage of voltage difference；The voltage and second threshold voltage are compared with output protection control signal, wherein,
The voltage of the 4th voltage signal and the voltage of tertiary voltage signal are compared into the result of acquisition and protection control signal is carried out
The first control signal is obtained after logic or computing；Wherein, the cycle of the sampled signal sampled to second voltage signal with
The cycle phase of control electromagnetic oven major loop switch conduction and the 3rd control signal for disconnecting is same, and for second voltage signal
Peak voltage is sampled.
Brief description of the drawings
Fig. 1 shows the operating diagram of electromagnetic oven.
Fig. 2 is the schematic diagram of the major loop of electromagnetic oven work in the prior art.
Fig. 3 is to calculate power by MCU in the prior art to adjust the signal of the working time and down time of switch W
Figure.
Fig. 4 represents the operation principle of resonance crest in the prior art using micro-control unit MCU controlling switches W.
Fig. 5 is voltage waveform when there is surge in electromagnetic oven work.
Fig. 6 shows that utilization simulation control part according to an exemplary embodiment of the present invention and digital control section are combined
To realize the schematic block circuit diagram of the control to the switch W on electromagnetic oven major loop.
Fig. 7 schematically shows the simulation control for electromagnetic oven shown in Fig. 6 according to an exemplary embodiment of the present invention
Partial block diagram.
Fig. 8 shows a specific example of the power control unit 710 shown in Fig. 7.
Fig. 9 A represent the waveform of each signal in resonance crest control section, and Fig. 9 B show each in resonance trough control section
The waveform of signal.
Figure 10 A show to carry out front and rear contrast and the input voltage vin of the resonance crest envelope before and after the control of resonance crest
Oscillogram.
Figure 10 B show to carry out front and rear contrast and the input voltage vin of the resonance trough envelope before and after the control of resonance trough
Oscillogram.
Figure 11 is that one kind of resonance potential control module in Fig. 8 according to a second embodiment of the present invention implements circuit.
Figure 12 A and Figure 12 B respectively illustrate each signal in resonance crest control section and resonance trough control section
Waveform.
Figure 13 shows the schematical electricity of the valley detection unit 720 shown in Fig. 7 according to an exemplary embodiment of the present invention
Lu Tu.
Figure 14 schematically shows the block diagram of the simulation control part according to another exemplary embodiment of the present invention.
Figure 15 shows the example of surge protection circuit.
Figure 16 A show electromagnetic oven major loop switch W control signal Gate, Figure 15 shown in surge protection circuit in open
Close the control signal S1 of K151, and the oscillogram for sensing ohmically voltage signal Vcs in electromagnetic oven major loop.
Figure 16 B show that the surge protection circuit according to Figure 15 carries out showing for the change of the voltage threshold after surge protection
Figure.
Figure 17 shows the schematic example of the combination between protection signal in protection control unit 1440.
Specific embodiment
Come to be described in detail the present invention below in conjunction with specific embodiments.Those skilled in the art should manage
Solution, the embodiment shown in the present invention is exemplary, is not intended as limitation of the present invention, meanwhile, provided in the present invention
Accompanying drawing only as illustrate purpose, its scope that should not unduly limit claims.Claim institute is not being departed from
In the case of the scope of protection, those skilled in the art can carry out adaptability on the basis of the embodiment being described in conjunction with the accompanying
Ground change, alternatives and modifications.
Show that utilization simulation control part according to an exemplary embodiment of the present invention is mutually tied with digital control section in Fig. 6
Close to realize the schematic block circuit diagram of the control to the switch W on electromagnetic oven major loop.
As shown in fig. 6, the resonance circuit being made up of magnet coil MC and capacitor C0 in input to the voltage after rectification
Also the series circuit being made up of resistance R61 and R62 is input into while one end, and at the node that the two resistance are connected
Voltage Vin is input into simulation control part and digital control section.In addition, the other end of resonance circuit and resistor R63 and R64
The series circuit and switch W for being constituted are connected, and the voltage Vw inputs at the node that resistor R63 is connected with R64
To simulation control part.
Digital control portion and simulation control part cooperate and set analog portion working condition.Digital control part to
Simulation control part transmission normal work enables signal Enable and reference voltage corresponding with the setting power of electromagnetic oven
Vref.In addition, in the case where simulation control part includes protection circuit, the digital control part can also be to simulation control
Transmit the threshold value Vth-oc and/or surge protection difference Vth-surge of the overcurrent protection for electromagnetic oven major loop switch W in part
Deng.Here, work enables signal Enable makes simulation control part normal work in high level with electromagnetic oven major loop
Switch W be controlled.After user sets to start shooting, digital control part detects from electromagnetic oven panel to be needed to start working
Then sent to simulation control part immediately and enable signal Enable to cause that simulation control part is operated.Switch the excessively stream of W
Rotection thresholds set Vth_oc and surge protection difference Vth_surge and can set different according to different induction cooker systems
Threshold value, to ensure the reliability of protection.
In addition, digital control part exports reference voltage corresponding with the power of user's setting to simulation control part
Vref, is controlled according to the reference voltage in order to simulation control part to the switch W on electromagnetic oven major loop.
As an example, simulation control part can to the voltage Vcs on digital control part output electric current measure resistance Rs,
Zero passage detection output signal ZDO, if simulation control part includes protection circuit, simulation control part is also to digital control part
Output protection control signal protection.Here, the zero passage detection of input signal Vin is realized by comparator, for example will
Input voltage vin is input into the inverting input of comparator, and the normal phase input end of comparator input predetermined voltage, so as to than
Compared with the output end output zero passage detection output signal ZDO of device.
According to an exemplary embodiment of the present, digital control part is by using the voltage Vcs's on current sense resistor Rs
The resistance value of average voltage Vcs-ave and current sense resistor Rs calculates average current Ics_ave, and by average current Ics_
Ave is multiplied to calculate the power that actually enters of electromagnetic oven with the average voltage Vin-ave of input voltage vin, and by electromagnetic oven
Power is actually entered to be compared to change the reference voltage Vref for being input to simulation control part with the power of user's setting
Value is controlled with to simulation control part, so that it is sufficiently small with the difference of setting power to actually enter power.Specifically,
Increase the value of reference voltage Vref if power is actually entered less than setting power, if power is actually entered more than setting power
Reduce the value of reference voltage Vref, untill the difference for actually entering power and setting power is sufficiently small.
In addition, according to an exemplary embodiment of the present, if simulation control part includes protection circuit, protecting control signal
Protection is then stored in the register (not shown in simulation control part) being included in simulation control part, and
And protection control signal protection, and the digital control portion after releasing is protected are read in digital control part from register
Dividing needs to enable signal Enable to simulation control part work, so that analog portion can restart work.Further, since
Input voltage vin minimum energy in resonance trough, so for security consideration, simulation control part enables signal in work
Enable and excessively zero output signal ZDO just start working when being high level.
Fig. 7 schematically shows the simulation control for electromagnetic oven shown in Fig. 6 according to an exemplary embodiment of the present invention
The block diagram of part processed.As shown in fig. 7, the simulation control part includes power control unit 710, valley detection unit 720, patrols
Collect control unit 730.Certainly, it should be appreciated by those skilled in the art that foregoing circuit can apply to any adaptable field
Conjunction is not limited solely to be controlled the power of electromagnetic oven.Below, the simulation control part is applied in order to describe easy
In electromagnetic oven power control.
Power control unit 710 receive corresponding with the setting power of electromagnetic oven reference voltage Vref and with electromagnetic oven master
The corresponding voltage signal of size of current (for example, the voltage signal Vcs on current sensing resistor Rs) on loop, pair and these
Voltage and the electricity of ramp signal ramp that the corresponding electric current of the voltage difference (i.e. error signal) of signal is integrated and then will obtain
Pressure is compared and exports the control signal off disconnected for controlling switch W with to logic control element 730, wherein, control signal
Off is level signal, and when control signal off is high level, the switch W that can control on electromagnetic oven major loop disconnects.
In addition, used as another example of the invention, power control unit 710 is also utilized draws electricity from electromagnetic oven major loop
Pressure signal Vw produces slope and then the ON time to switching W that compensation electric current changes ramp signal to be controlled.
Valley detection unit 720 receiving voltage signal Vw and Vin, and voltage signal Vw and Vin are compared, while will
The voltage of the voltage change of reflecting voltage signal Vw is compared with predetermined threshold Vth, based on above-mentioned two comparative result to patrolling
Collect control unit 730 and export the control signal on turned on for controlling switch W.Wherein, control signal on is level signal.Work as control
When signal on processed is high level, controllable switch W conductings.
Logic control element 730 is based on the control letter for being exported from power control unit 710 and valley detection unit 720 respectively
Number off and control signal on exports the control signal Gate of conducting and disconnection for controlling switch W.
As an example, logic control element 730 is rest-set flip-flop, the output of power control unit 710 is connected to RS triggerings
The reset terminal of device, and the output of valley detection unit 720 is connected to the set end of rest-set flip-flop.That is, control signal off
It is input to the reset terminal of rest-set flip-flop and control signal on is input to the set end of rest-set flip-flop.The output end Q of rest-set flip-flop connects
The control end of switch W is connected to the conducting and disconnection of controlling switch W.Here, only as an example and without limitation, switch W can
Think that insulated gate bipolar transistor is switched.
Fig. 8 shows a specific example of the power control unit 710 shown in Fig. 7.
As shown in figure 8, power control unit 710 includes difference integrating circuit 810, ramp signal generator 820 and compares
Device 830.Difference integrating circuit 810 includes operation transconductance amplifier gm and capacitor C81.Will be corresponding to the setting power of electromagnetic oven
Reference voltage Vref and voltage signal Vcs operation transconductance amplifier gm is input to pair (to be missed with the voltage difference of these signals
Difference signal) corresponding electric current is integrated.Wherein, reference voltage Vref corresponding with setting power is input to operation transconductance amplification
The normal phase input end of device gm and voltage signal Vcs is input to the inverting input of operation transconductance amplifier gm with defeated according to the two
Enter the voltage difference between signal to adjust the size of output current.The output end of operation transconductance amplifier gm is connected to capacitor
C81, so as to be integrated to the electric current exported from operation transconductance amplifier gm using capacitor C81, is obtained on capacitor C81
Voltage signal comp.In addition, voltage signal comp is input to the inverting input of comparator 830.
Ramp signal generator 820 can be used to generate ramp signal ramp, and ramp signal ramp is input into comparing
The normal phase input end of device 830.The ramp signal ramp that comparator 830 generates ramp signal generator 820 is integrated with from difference
The voltage signal comp of the output of circuit 810 is compared, with to the output control signal of logic control element 730 shown in Fig. 7
off.When ramp signal ramp voltage higher than comp signals voltage when, export from comparator 830 (namely from Power Control list
Unit 710 export) control signal off be changed into high level so that from logic control element 730 output control signal Gate
The switch W being changed into low level, therefore electromagnetic oven major loop disconnects.
Used as simple examples, ramp signal generator 820 may include electric capacity C82, current source and switch K81.Wherein, slope
Signal ramp changes synchronous with control signal Gate.When W conductings are switched, namely during control signal Gate output high level, open
Close K81 to disconnect, electric capacity C82 is charged by current source, the voltage of ramp signal ramp is gradually increasing；When W disconnections are switched,
That is during control signal Gate output low levels, switch K81 conductings, by switching K81 to electric capacity C82 repid discharges, ramp signal
The voltage of ramp drastically drops to 0.
In accordance with an alternative illustrative embodiment of the present invention, the ramp signal generator 820 may also include by resonance crest
The resonance potential control circuit that at least one of control circuit and resonance wave paddy control circuit are constituted.The resonance potential control
Circuit is used to be provided according to resonance potential value the compensation electric current of the slope for changing ramp signal ramp.When W conductings are switched,
Namely during control signal Gate output high level, switch K81 disconnects, constant current i and the resonance potential of current source output are controlled
The compensation electric current of circuit output charges to capacitor C2 together, and the voltage of ramp signal ramp is gradually increasing.
Fig. 8 shows that resonance crest control circuit and resonance wave paddy control a kind of example of circuit.Resonance crest control unit
The waveform of each signal is as shown in Figure 9 B as shown in Figure 9 A, in resonance trough control section for the waveform of each signal in point.
In resonance crest control circuit, the switching voltage Vw on one end input electromagnetic oven major loop of K82 is switched (as schemed
Shown in 6), the switch K82 other ends are connected with capacitor C83, the other end ground connection of capacitor C83.As an example, capacitor C83
Capacitance can be 10pF.One end that switch K82 is connected with capacitor C83, its inverting input is connected to end is output it
And the normal phase input end for constituting the operational amplifier of the first follower circuit is connected.Switch K82 is by the control of crest sampled signal
It is turned on or off, crest sampled signal is a pulse signal, as shown in Figure 9 A, when voltage signal Vw is in ripple within each cycle
During peak position, the crest sampled signal is high level, switch K82 conductings.When switch K82 turn on when, capacitor C83 with switch
K82 connected one end is the instantaneous value Vs1 of the peak voltage of resonance potential Vw；When switch K82 disconnects, still protected on capacitor C83
Hold peak voltage Vs1, and input operational amplifier normal phase input end.The output end of operational amplifier and its inverting input
It is connected, and is connected to a RC integrating circuit being made up of resistor R81 and capacitor C84, wherein resistor R81 and capacitor
The node that C84 is connected is connected with the normal phase input end of first voltage control electric current source vccs1.Voltage Vc1 on capacitor C84
The normal phase input end of input first voltage control electric current source vccs1.First reference voltage Vref 1 is input into first voltage control electric current
The inverting input of source vccs1, first voltage control electric current source vccs1 generations and voltage Vc1 and the first reference voltage Vref 1 it
Between the directly proportional first compensation electric current i1 of voltage difference, the constant current i phases that the first compensation electric current i1 is exported with current source
In addition after, charge generation ramp signal ramp to capacitor C82.
As another example, in above-mentioned resonance crest control circuit, it is also possible to do not need the first follower circuit, remaining
Partial circuit is constant.That is, one end that switch K82 is connected with capacitor C83, directly constitutes with resistor R81 and capacitor C84
RC integrating circuit be connected, the normal phase input end of voltage Vc1 on capacitor C84 input first voltage control electric current source vccs1.
In resonance trough control circuit, the switching voltage Vw on one end input electromagnetic oven major loop of K83 is switched (as schemed
Shown in 6), the other end is connected with capacitor C85, the other end ground connection of capacitor C85.As an example, the capacitance of capacitor C85
Can be 10pF.One end for being connected with capacitor C85 of switch K83, its inverting input is connected to so as to constitute the with its output end
The normal phase input end of the operational amplifier of two follower circuits is connected.Switch K83 is controlled by trough sampled signal and is led on-off
Open, trough sampled signal is a pulse signal, as shown in Figure 9 B, when the Gate signals of the switch W of control electromagnetic oven major loop
Within each cycle at the end of, the trough sampled signal is high level, switch K83 conductings to low level.When switch K83 leads
When logical, one end that capacitor C85 is connected with switch K83 is the peak voltage Vs2 of resonance potential Vw；When switch K83 disconnects, electric capacity
Still keep peak voltage Vs2 on device C85, and input operational amplifier normal phase input end.The output end of operational amplifier with
Its inverting input is connected, and is connected to the RC integrating circuit being made up of resistor R82 and capacitor C86, wherein resistor R82
The node being connected with capacitor C86 is connected with the normal phase input end of second voltage control electric current source vccs2.On capacitor C86
Voltage Vc2 inputs second voltage control electric current source vccs2 normal phase input end.The electricity of the input of second reference voltage Vref 2 second
The inverting input of voltage-controlled current source vccs2, second voltage control electric current source vccs2 generations and the references of voltage Vc2 and second
Voltage difference directly proportional second compensation electric current i2, the second compensation electric current i2 and current source output between voltage Vref2
After constant current i subtracts each other, charge generation ramp signal ramp to capacitor C2.
In above-mentioned resonance trough control section, it is also possible to do not need second follower circuit, the circuit of remainder
It is constant.That is, one end that switch K83 is connected with capacitor C85, the RC for directly being constituted with resistor R82 and capacitor C86 integrates electricity
Road is connected, the normal phase input end of the voltage Vc2 input second voltage control electric currents source vccs2 on capacitor C86.
In the first embodiment, the slope of ramp signal ramp is adjusted by the method for closed loop, so as to by resonance potential
Crest and trough are controlled near the first reference voltage Vref 1 and the second reference voltage Vref 2 respectively.
Figure 10 A show the front and rear contrast and input voltage for carrying out the resonance crest envelope before and after the control of resonance crest
The oscillogram of Vin (as shown in Figure 6).As shown in Figure 10 A, if being added without the crest control of resonance potential, resonance potential on switch W
Crest envelope be rendered as sine wave with the change of input voltage vin；When input voltage vin is in crest, resonance potential
Also by the crest location in resonance potential crest envelope, now resonance potential will exceed set in advance first with reference to electricity
Pressure.After adding resonance peak voltage to control, if the crest of resonance potential is more than the first reference voltage, it will by increasing slope
The slope of signal ramp and reduce Ton, the crest of resonance potential is held in the first reference voltage Vref 1.
Figure 10 B show the front and rear contrast and input voltage for carrying out the resonance trough envelope before and after the control of resonance trough
The oscillogram of Vin.If the trough to resonance potential is not controlled, the trough of resonance potential is with input voltage vin on switch W
The change of (as shown in Figure 6) and be rendered as sine wave；When input voltage vin is in crest, resonance potential also will be in resonance
The crest location of voltage trough envelope, resonance potential now will be more than the second reference voltage Vref 2.When addition resonance trough
After voltage control, if the trough of resonance potential is more than the second reference voltage Vref 2, it will by reducing the oblique of ramp signal ramp
Rate and extend Ton so that the trough of resonance potential is controlled in the second reference voltage.
Because when the control of resonance potential is carried out, induction cooker system need to keep power set in advance, therefore electromagnetic oven
In circuit system can automatically adjust, the peak voltage of resonance and peak voltage is respectively retained the first reference voltage Vref 1
With the time near the second reference voltage Vref 2, be compared to the ripple for not carrying out resonance potential under conditions of resonance potential control
The time of peak and trough respectively more than the first reference voltage and the second reference voltage is longer.Reflect in oscillogram, Ke Yizhi
See ground to see, after resonance potential control is added, resonance peak voltage and peak voltage will quickly rise to the first ginseng respectively
Voltage Vref1 and the second reference voltage Vref 2 are examined, and respectively from the first reference voltage Vref 1 and the second reference voltage Vref 2
The speed of decline also will faster.
Figure 11 is that one kind of resonance potential control module in Fig. 8 according to a second embodiment of the present invention implements circuit.
It should be appreciated by those skilled in the art that the circuit structure shown in Figure 11 is only example, it should not unduly limit claim
The scope of book.Those skilled in the art can fit on the premise of exemplary embodiment of the present is not departed to embodiment
The change of answering property, alternatives and modifications.
Resonance potential control circuit in the second embodiment includes resonance crest control section and resonance wave paddy control unit
At least one of point.The waveform of each signal is as illustrated in fig. 12, each in resonance trough control section in resonance crest control section
The waveform of signal is as shown in Figure 12 B.
In resonance crest control section according to a second embodiment of the present invention, one end input electromagnetic oven master of K111 is switched
The voltage Vw (as shown in Figure 6) of the switch on loop, the other end is connected with capacitor C111, another termination of capacitor C111
Ground.As an example, the capacitance of capacitor C111 can be 10pF.One end for being connected with capacitor C111 of switch K111, and compares
The normal phase input end of device is connected.Switch K111 is controlled and is turned on or off by crest sampled signal, identical with first embodiment, should
Crest sampled signal is a pulse signal, and when Vw is in crest location within each cycle, the crest sampled signal is electricity high
It is flat, switch K111 conductings.When K111 conductings are switched, one end that capacitor C111 is connected with switch K111 is resonance potential Vw's
The instantaneous value Vs1 of peak voltage；When K111 disconnections are switched, peak voltage Vs1 is still kept on capacitor C111, and be input into ratio
Compared with the normal phase input end of device.The inverting input of the input comparator of the first reference voltage Vref 1.When voltage Vs1 is more than the first ginseng
When examining voltage Vref1, comparator exports the pulse signal Ts1 of a high level with controlling switch K112.The input voltage of electromagnetic oven
Vin (as shown in Figure 6) is by switching K112 input capacitor C112, the other end ground connection of capacitor C112.As an example, electric capacity
The capacitance of device C112 can be 10pF.Pulse signal Ts1 controls the conducting and disconnection of switch K112.When the pulse signal
When Ts1 is high level, switch K112 conductings, (namely capacitor C112's voltage on capacitor C112 is connected with K112 is switched
The voltage of one end) it is the instantaneous value V1 of input voltage vin；When switch K112 disconnects, voltage V1 is still kept on capacitor C112,
And it is input into the inverting input of first voltage control electric current source vccs1.Input voltage vin input first voltage control electric current source
The normal phase input end of vccs1.First voltage control electric current source vccs1 is generated and the difference between input voltage vin and voltage V1
Directly proportional first compensation electric current i1, after the constant current i that the first compensation electric current i1 is exported with current source is added, to electric capacity
Device C2 charges and generates ramp signal ramp.
In resonance trough control section, the voltage Vw of the switch W on one end input electromagnetic oven major loop of K113 is switched,
The other end is connected with capacitor C113, the other end ground connection of capacitor C113.As an example, the capacitance of capacitor C113 can be
10pF.One end that switch K113 is connected with capacitor C113, is connected with the normal phase input end of comparator.Switch K113 is adopted by trough
Sample signal is controlled and is turned on or off.Identical with first embodiment, the trough sampled signal is a pulse signal, when control electromagnetism
Within each cycle at the end of, the trough sampled signal is height to the low level of the Gate signals of the switch W of stove major loop
Level, switch K113 conductings.When K113 conductings are switched, one end that capacitor C113 is connected with switch K113 is resonance potential Vw
Peak voltage Vs2；When switching K113 and disconnecting, peak voltage Vs2 is still kept on capacitor C113, and input comparator
Normal phase input end.The inverting input of the input comparator of the second reference voltage Vref 2.When voltage Vs2 is more than the second reference voltage
During Vref2, comparator exports the pulse signal Ts2 of a high level with controlling switch K114.The input voltage vin of electromagnetic oven passes through
Switch K114 is connected with capacitor C114, the other end ground connection of capacitor C114.As an example, the capacitance of capacitor C114 can
It is 10pF.Pulse signal Ts2 controls the conducting and disconnection of switch K114.When pulse signal Ts2 is high level, switch
K114 is turned on, and one end that capacitor C114 is connected with switch K114 is the instantaneous value V2 of input voltage vin；When switch K114 breaks
Open, voltage V2 is still kept on capacitor C114, and be input into the inverting input of second voltage control electric current source vccs2.Input
The normal phase input end of voltage Vin input second voltage control electric currents source vccs2.Second voltage control electric current source vccs2 generate with
The directly proportional second compensation electric current i2 of difference between input voltage vin and voltage V2, the second compensation electric current i2 and current source
After the constant current i of output subtracts each other, charge generation ramp signal ramp to capacitor C2.
If the crest of resonance potential when uncontrolled is higher, when adding crest to control, the crest of resonance potential " is cut
It is flat " must be more, in order to the power for ensureing electromagnetic oven does not change, in reflection to the oscillogram of the resonance potential after " scabbling ",
The time that voltage Vs1 rises to the first reference voltage Vref 1 will be shorter.For these reasons, if resonance when uncontrolled is electric
The crest of pressure is higher, when adding crest to control, moment when Vs1 is more than the first reference voltage Vref 1, i.e. pulse signal Ts1
It it is the moment of high level, the phase angle corresponding to input voltage vin is smaller.Due to being got over hour at phase angle, input voltage change
It is faster, therefore phase angle is smaller, the first compensation electric current i1 being added on electric current i is bigger, and the Ton times reduce more；It is based on
Identical the reason for, if the trough of resonance potential when uncontrolled is higher, the trough of resonance potential is more than the second reference voltage
The phase angle at the moment of Vref2 will be smaller, bigger with the second compensation electric current i2 that electric current i subtracts each other, and the Ton times increase must get over
It is many.
Therefore, second embodiment resonance potential control circuit under, the size of current compensation amount be added without compensate bar
The crest of resonance potential is related to the height of trough under part.Input first voltage control electric current source vccs1 and second voltage
Two differences of voltage of control electric current source vccs2 and the ratio for producing the first compensation electric current i1 and the second compensation electric current i2, will
Have influence on the control effect of resonance potential.
From foregoing formula (4), formula (6), the crest and trough for switching the resonance potential of W are the letters of time Ton
Number, specifically, the crest and trough of resonance potential increase and reduce respectively with the increase of Ton.As shown in Figure 8 and Figure 11 humorous
Vibration wave peak controls circuit and resonance wave paddy control circuit exactly to make use of this characteristic to be controlled switch W.When switch W's
When resonance potential crest is more than the first reference voltage Vref 1, the slope of increase ramp signal ramp makes the electricity of ramp signal ramp
Press and shorten more than the time Ton needed for the voltage of comp signals, so as to reduce the resonance potential crest on switch W；When switch W's
When the trough of resonance potential is more than the second reference voltage Vref 2, reduce the slope of ramp signal ramp, make ramp signal ramp's
Voltage extends more than the time Ton needed for the voltage of comp signals, so as to reduce the trough of the resonance potential on switch W.
Figure 13 is show valley detection unit 720 shown in Fig. 7 according to an exemplary embodiment of the present invention schematical
Circuit diagram.
As an example, valley detection unit 720 can include capacitor C130, resistor R130, comparator Com130.Its
Middle capacitor C130 one end is connected with resistor R130, the other end input voltage signal Vw, capacitor C130 and resistor
The node that R130 is connected is connected to the inverting input of comparator Com130, and the normal phase input end of comparator Com130 is input into
Threshold voltage vt h.Comparator Com130 is compared to the voltage being input into, when in input to inverting input with switch W
When the corresponding voltage of voltage is less than threshold voltage vt h, comparator Com130 output high level signals.Here, voltage signal Vw warps
The electric current for representing resonance potential (the voltage signal Vw after switch W disconnections) slope, the electric current are produced after crossing capacitor C130 differential
The voltage for flowing through resistor R130 generations has been similarly represented as the slope of resonance potential.When the electricity that current flows through resistor R130 is produced
Pressure is less than threshold voltage VthWhen, representing resonance and arrived or close to trough, comparator Com130 exports high level.Can be by this signal
The signal on turned on as the switch W on control electromagnetic oven major loop is input into logic control circuit 730.
In addition, as shown in figure 13, the valley detection unit 720 can also include comparator Com131 and with door.At this
In the case of kind, voltage signal Vw also inverting inputs of input comparator Com131 while input capacitor C130, and it is defeated
Enter the normal phase input end of voltage Vin inputs (as shown in Figure 6) to comparator Com131.When the magnitude of voltage of input voltage vin is higher than
During the magnitude of voltage of voltage signal Vw, comparator Com131 output high level signals.From comparator Com130 and Com131 output
Signal input is to, to carry out logic and operation, the level signal exported with door is used as input to logic control element 730 with door
Level signal on to the switch W on electromagnetic oven major loop so as to be controlled.Add comparator Com131 and be based on such as with door
Lower described consideration：Voltage signal Vw is the resonance potential centered on input voltage vin, and the mode of detectable voltage signals Vw is adopted
With slope detection, but the slope of the voltage of voltage signal Vw can all be less than threshold voltage vt h at crest and trough, at this
Another Rule of judgment Vc ＜ Vin are added in circuit more accurately can be judged trough.
Figure 14 schematically shows the mould for electromagnetic oven according to Fig. 6 of another exemplary embodiment of the present invention
Intend the block diagram of control section.As shown in figure 14, the simulation control part includes power control unit 1410, valley detection unit
1420th, logic control element 1430 and protection control unit 1440.Power control unit 1410 wherein, shown in Figure 13,
Valley detection unit 1420, logic control element 1430 can be examined with the power control unit 710, trough shown in Fig. 7 respectively
Surveying unit 720 and logic control element 730 has identical circuit structure.Protection control unit 1440 shown in Figure 14 is used for
Controlling circuit of electromagnetic furnace is effectively protected.The protection control signal protection of protection control unit 1440 output
The level signal off exported with power control unit 1410 is input to the (example of logic control element 1430 after carrying out logic or computing
Such as it is input to the reset terminal of rest-set flip-flop), it is controlled with to electromagnetic oven major loop switch W.
As an example, the protection control unit 1440 may include surge protection circuit schematic diagram as shown in figure 15.This
It should be understood that the circuit structure shown in Figure 15 is only example, it should not unduly limit claims to art personnel
Scope.Those skilled in the art can adaptively be changed on the basis of the diagram, alternatives and modifications.
As an example, the surge protection circuit shown in Figure 15 includes voltage follow sample circuit 1510, differential amplifier circuit
1520 and comparator 1530.
Sample circuit 1510 includes voltage follower, K151 and sampling capacitance C151 of switch.The voltage follower bag
Containing an operational amplifier op, the voltage signal V on current sensing resistor Rs on electromagnetic oven major loopcsIt is input into the operation amplifier
The normal phase input end of device, the inverting input of the operational amplifier is connected with its output end, and the output of operational amplifier is this
The output of voltage follower.The output end of the voltage follower is connected by switch K151 with sampling capacitance C151.Due to
The multiplication factor of voltage follower is permanent to be less than and close to 1, therefore the output voltage of the voltage follower is approximately Vcs。
The output end of voltage follower is connected with switch K151, and the other end for switching K151 is connected with sampling capacitance C151,
The other end ground connection of sampling capacitance C151.Switch K151 is turned on or off by such as the sampled signal S1 controls in Figure 15, wherein
The cycle phase of the Gate signals that the cycle of sampled signal S1 turns on and disconnects with controlling switch W is same, when Gate signals are electricity high
At the end of, S1 is high level to the flat and high level signal.When S1 is high level, switch K151 closures；When S1 is low
During level, switch K151 disconnects, and the output voltage of voltage follower when now sampling capacitance C151 maintained switch K151 is closed should
The voltage V being keptcsIt is the peak voltage V in each cycle of Gate signalscs_pk。
As an example, differential amplifier circuit 1520 includes operation transconductance amplifier gm and resistor R151.Switch K151
The node being connected with sampling capacitance C151, the inverting input with operation transconductance amplifier gm is connected, and operation transconductance amplifies
The anti-phase input of device gm is the output voltage V of sample circuit 1510cs_pk, i.e., the voltage crest in the upper cycle of Gate signals；
Voltage V in Gate signal current periodscsThe normal phase input end of input operation transconductance amplifier gm (as shown in Figure 6), the computing
The output end of trsanscondutance amplifier gm is connected with resistor R151, the other end ground connection of resistor R151.
The node that the output end of differential amplifier circuit 1520 is connected with resistor R151 is input into the positive of comparator 1530
End is connected, and the inverting input input voltage difference Vth_surge of comparator 1530 is output as control signal Surge-off.Fortune
Trsanscondutance amplifier gm is calculated according to Vcs_pkAnd VcsBetween voltage difference, according to predetermined ratio generate electric current；The electric current is by resistance
Device R151, produces pressure drop；Therefore, differential amplifier circuit 1520 is exported and Vcs_pkAnd VcsBetween the corresponding voltage of voltage difference, when
Voltage difference V of the voltage more than the input of the inverting input of comparator 1530th_surgeWhen, control signal Surge-off becomes
It is high level, controlling switch W disconnects.
Figure 16 A are shown in the surge protection circuit shown in control signal Gate, Figure 15 of electromagnetic oven major loop switch W
The control signal S1 of K151 is switched, and the oscillogram of voltage signal Vcs on resistance is sensed in electromagnetic oven major loop.
As shown in Figure 16 A, Gate signals are used for the conducting and disconnection of controlling switch W.When Gate signals are high level, open
W conductings are closed, the forward current that magnet coil flows through increases, the electric current for flowing through resistance Rs increases, thus voltage VcsIncrease, currently adopts
Voltage V in the sample cyclecsThreshold voltage Vthoc1It is the voltage V obtained by sampling within a upper sampling periodcsOn the basis of fold
Power-up pressure difference Vth_surgeObtain.
As shown in fig 16b, sample the voltage V for obtainingcsEnvelope be a sinusoidal waveform.Sampled within a upper sampling period
The voltage V for arrivingcsOn the basis of superimposed voltage difference Vth_surge, obtain voltage V in current sample periodcsThreshold voltage
Vthoc1。_surgeVthoc1
Due under conditions of induction cooker system normal work, voltage VcsWill not undergo mutation, by the way that upper one sampling is all
The voltage V of phase samplingcsSuperimposed voltage difference Vth_surgeAs threshold voltage V in current sample periodthoc1Mode, can be to electricity
Magnetic furnace system provides the overcurrent protection under all power and phase condition, and compared with numerical protection mode, its reflection is protected
The shield time greatly shifts to an earlier date, reliable much sooner.Here, if by threshold voltage Vthoc1Certain fixed value is set to, for example, by the first threshold
Threshold voltage Vthoc1It is set asWhereinIt is voltage Vcs in the peak voltage of its envelope, Δ V is fixed
Magnitude of voltage, when there is surge at the bottom of envelope as shown in fig 16b or half waist, it would be possible to cannot in time disconnect switch W
And protection is provided, and surge protection circuit as shown in figure 15 added voltage difference by by the sampled voltage in a upper cycle
Vth_surge, this point can be prevented effectively from.
As an example, the protection control unit 1440 may additionally include usually used input in controlling circuit of electromagnetic furnace
In electric voltage over press protection circuit (Vin OVP), current foldback circuit (OCP), switching voltage overvoltage crowbar (Vw OVP)
At least one, because above-mentioned protection circuit is the very familiar curtage protection circuit of those skilled in the art,
These protection circuits will not be described in detail in the present invention.Include input voltage mistake in the protection control unit 1440
Voltage protection circuit (Vin OVP) (being realized by the way that input voltage vin is compared with predetermined voltage), current foldback circuit
(OCP) (realized by the way that voltage Vcs is compared with predetermined voltage), switching voltage overvoltage crowbar (Vw OVP) (passes through
Voltage Vw is compared with predetermined voltage and is realized) at least one of in the case of, by the output to these protection circuits
Pro-off (is after carrying out logic or computing to each output of multiple protection circuits in the case where there is multiple protection circuits
Output) carry out logic or computing with the output surge-off of surge protection circuit and obtain protecting control signal
Protection, by the output control by control signal protection and power control unit 1410 as shown in figure 14 is protected
Signal off processed carries out logic or computing and is input to the reset terminal of the logic control element 1430 shown in Figure 14 so as to electromagnetic oven
The switch W of major loop is controlled.Figure 17 shows the schematic of the combination between the protection each protection signal of control unit 1440
Example.
According to an exemplary embodiment of the present, because using power control unit as shown in Figure 8, it is possible to achieve electromagnetic oven
Can continuously be worked incessantly in full voltage input range and under different set power, so as to realize to the fast of pot
Speed heating, so as to save electric energy.According to an exemplary embodiment of the present, technical scheme is applied to different capacity etc.
The induction cooker system of level, can be on the premise of electromagnetic oven output power not be influenceed, the crest of effective control resonance potential, it is to avoid
Switch on electromagnetic oven major loop is damaged because of overvoltage, while the trough of resonance potential can also be controlled, is reduced on major loop
The turn-on consumption of switch, it is to avoid the switch aircraft bombing of electromagnetic oven.
In addition, according to an exemplary embodiment of the present, digital control part by by electromagnetic oven actually enter power with
The power of user's setting is compared to change the value of the reference voltage Vref for being input to simulation control part with to simulation control
Part is controlled, it is achieved thereby that actually entering the dynamic regulation of power.Meanwhile, by the analog circuit using closed-loop fashion
The power of electromagnetic oven can more accurately and quickly be controlled.
In addition, according to an exemplary embodiment of the present, by the voltage V that a upper sampling period samplescsSuperimposed voltage is poor
Value Vth_surgeAs threshold voltage V in current sample periodthoc1Mode, induction cooker system can be provided in all power and
Overcurrent protection under phase condition, and compared with numerical protection mode, its reflection guard time greatly shifts to an earlier date, and much sooner may be used
Lean on.
Additionally, although the present invention and its advantages have been described in detail, it is to be understood that can be without departing substantially from appended right
It is required that in the case of the spirit and scope of the present invention for limiting, carrying out a variety of changes, replacement and change；And, the present invention
The scope system, the embodiment of method and steps that are not limited in described in this specification.As ordinary skill people of the present invention
Member should be understood that by the present invention, existing or Future Development for execution and according to the technical solution adopted in the present invention base
The method and steps of this identical mode or the essentially identical result of acquisition can be used according to the present invention.
Claims (25)
1. a kind of control circuit for electromagnetic oven, including：
Digital control part, according to the rectified input voltage corresponding first with electromagnetic oven received from simulation control part
Voltage signal and second voltage signal of change electromagnetic oven corresponding with electromagnetic oven main circuit current actually enter power, and will
The power that actually enters of electromagnetic oven is compared to change the first reference voltage cause electromagnetic oven with the power of user's setting
Actually enter power sufficiently small with the difference of setting power, and first reference voltage is input into simulation control part；
Simulation control part, based on the first reference voltage being input into from digital control part and with electromagnetic oven main circuit current phase
The second voltage signal answered is controlled to electromagnetic oven major loop switch.
2. it is as claimed in claim 1 to control circuit, wherein, the analog control circuit includes：
First control unit, electric current corresponding with the voltage difference between the voltage of the first reference voltage and second voltage signal is entered
Row integration obtains tertiary voltage signal, and using as the electricity of the voltage of the 4th voltage signal of ramp signal and tertiary voltage signal
Pressure is compared to export the first control signal；
Second control unit, the voltage and the first threshold of the 6th voltage signal based on the voltage change by the 5th voltage signal is reflected
Result and comparative result output the second control letter by first voltage signal and the 5th voltage signal that threshold voltage is compared
Number；
Logic control element, exports the 3rd control signal and is returned with to electromagnetic oven master based on the first control signal and the second control signal
Way switch is controlled,
Wherein, the 5th voltage signal is corresponding to the voltage being applied on electromagnetic oven major loop switch.
3. it is as claimed in claim 2 to control circuit, wherein, first control unit includes：
Resonance crest controls circuit, and the resonance peak voltage to electromagnetic oven major loop switch is sampled, and is obtained using sampling
Resonance peak voltage generation first compensates electric current,
First control unit is added profit with constant current by the way that resonance crest to be controlled the first compensation electric current of circuit evolving
Electricity container is generated as the 4th voltage signal of ramp signal.
4. it is as claimed in claim 3 to control circuit, wherein, first control unit also includes：
Resonance trough controls circuit, and the resonance peak voltage to electromagnetic oven major loop switch is sampled, and is obtained using sampling
Resonance peak voltage generation second compensates electric current,
Wherein, first control unit controls the second of circuit evolving to compensate electric current phase by by constant current and resonance trough
Subtract the 4th voltage signal by the use of capacitor generation as ramp signal.
5. it is as claimed in claim 4 to control circuit, wherein, in resonance crest control circuit, by a RC integrating circuit
The normal phase input end in the resonance crest control source first voltage control electric current source that sampling is obtained, and the second reference voltage is defeated
Enter the inverting input in first voltage control electric current source to generate the first compensation electric current.
6. it is as claimed in claim 5 to control circuit, wherein, in resonance trough control circuit, by the 2nd RC integrating circuit
The normal phase input end in the resonance peak voltage input second voltage control electric current source that sampling is obtained, and the 3rd reference voltage is defeated
Enter the inverting input in second voltage control electric current source to generate the second compensation electric current.
7. it is as claimed in claim 6 to control circuit, wherein, in resonance crest controls circuit and resonance wave paddy control circuit,
Voltage follower circuit is utilized respectively by the control source that obtains to a RC integrating circuit and the 2nd RC integrating circuit of sampling.
8. it is as claimed in claim 4 to control circuit, wherein, in resonance crest control circuit, the resonance wave that sampling is obtained
Peak voltage relatively generates the first pulse signal compared with the 4th reference voltage, using the first pulse signal first voltage signal is entered
Row sampling, and the first voltage signal that first voltage signal and sampling are obtained is separately input to tertiary voltage control electric current source
Normal phase input end and inverting input are generating the first compensation electric current.
9. it is as claimed in claim 5 to control circuit, wherein, in resonance trough control circuit, the resonance wave that sampling is obtained
Valley voltage relatively generates the second pulse signal compared with the 5th reference voltage, using the second pulse signal first voltage signal is entered
Row sampling, and the first voltage signal that first voltage signal and sampling are obtained is separately input to the 4th VCCS
Normal phase input end and inverting input are generating the second compensation electric current.
10. it is as claimed in claim 2 to control circuit, wherein, the logic control element is rest-set flip-flop, and the first control signal is defeated
Enter the reset terminal to rest-set flip-flop, and the second control signal is input to the set end of rest-set flip-flop, when the first control signal is height
During level, the 3rd control signal from logic control element output is low level, and electromagnetic oven major loop is switched off；When the second control
When signal processed is high level, the 3rd control signal from logic control element output is high level, and electromagnetic oven major loop switch is led
It is logical.
11. control circuits as claimed in claim 2, wherein, the analog control circuit also includes：
3rd control unit, for producing protection control signal, the 3rd control unit to include surge protection circuit, the wave
Gushing protection circuit includes：
Sample circuit, is sampled to second voltage signal and sampled second voltage signal is believed as the first output voltage
Number output；
Differential amplifier circuit, obtains voltage corresponding with the voltage difference between second voltage signal and the first output voltage signal；
First comparator, the voltage and second threshold voltage is compared to export the 4th control as protection control signal
Signal,
Wherein, the result and protection that the voltage of the voltage of the 4th voltage signal and tertiary voltage signal is compared acquisition are controlled
Signal carries out obtaining the first control signal after logic or computing；
Wherein, the cycle of the sampled signal that sample circuit is sampled to second voltage signal and control electromagnetic oven major loop switch
The cycle phase of conducting and the 3rd control signal for disconnecting is same, and is sampled for the peak voltage to second voltage signal.
12. control circuits as claimed in claim 11, wherein, sample circuit includes the voltage follow being made up of operational amplifier
Device, first switch and the first capacitor, the output end of the voltage follower are connected by first switch with the first capacitor, and first
The other end ground connection of capacitor, the voltage signal on the first capacitor is input to differential amplification electricity as the first output voltage signal
Road；Second voltage signal input to the operational amplifier normal phase input end.
13. control circuits as claimed in claim 12, wherein, the 3rd control unit also mistake including first voltage signal
The overvoltage of the switching voltage on voltage protection circuit, the current foldback circuit of electromagnetic oven main circuit current, electromagnetic oven major loop switch
At least one of protection circuit protection circuit, wherein, the overvoltage crowbar of the first voltage signal passes through first voltage
Signal realizes that the current foldback circuit of the electromagnetic oven main circuit current passes through will be with electromagnetism compared with the first predetermined voltage
The corresponding voltage of stove main circuit current realizes that the overvoltage crowbar of the switching voltage leads to compared with the second predetermined voltage
Cross the voltage that will reflect on electromagnetic oven major loop switch to be compared with the 3rd predetermined voltage and realized, by the 3rd control unit
In the output of protection circuit that includes carry out obtaining protection control signal after logic or computing.
14. control circuits as claimed in claim 2, wherein, second control unit includes the second capacitor and the first electricity
Resistance device, the 6th voltage signal produced at the node that second capacitor is connected with first resistor device is input into second and compares
Device is compared with first threshold voltage, wherein, when the voltage of the 6th voltage signal is less than first threshold voltage and first
It is high level that voltage signal is more than the second control signal exported during five voltage signals.
A kind of 15. electromagnetic ovens of the control circuit including as described in any one of claim 1-14.
A kind of 16. control methods for electromagnetic oven, including：
According to the corresponding first voltage signal of rectified input voltage with electromagnetic oven and with electromagnetic oven main circuit current phase
The second voltage signal of change electromagnetic oven answered actually enters power, and electromagnetic oven is actually entered into power with user's setting
Power be compared to change the first reference voltage with so that electromagnetic oven to actually enter power enough with the difference of setting power
It is small；
Electromagnetic oven major loop switch is controlled based on the first reference voltage and second voltage signal.
17. control methods as claimed in claim 16, wherein, it is described to be based on the first reference voltage and second voltage signal pair
The step of electromagnetic oven major loop switch is controlled includes：
Electric current corresponding with the voltage difference between the voltage of the first reference voltage and second voltage signal is integrated acquisition
Three voltage signals, and using as the voltage of the 4th voltage signal of ramp signal and the voltage of tertiary voltage signal be compared with
Export the first control signal；
The voltage of the 6th voltage signal based on the voltage change by the 5th voltage signal is reflected is compared with first threshold voltage
Compared with result and the comparative result of first voltage signal and the 5th voltage signal exported into the second control signal；And
The 3rd control signal is exported based on the first control signal and the second control signal to be controlled with to electromagnetic oven major loop switch
System,
Wherein, the 5th voltage signal is corresponding to the voltage being applied on electromagnetic oven major loop switch.
18. control methods as claimed in claim 17, wherein, the resonance peak voltage to electromagnetic oven major loop switch is adopted
Sample, the resonance peak voltage generation first obtained using sampling compensates electric current, and electric current and constant current phase are compensated by by first
Plus by the use of capacitor generation as the 4th voltage signal of ramp signal.
19. control methods as claimed in claim 18, wherein, the resonance peak voltage to electromagnetic oven major loop switch is adopted
Sample, the resonance peak voltage generation second obtained using sampling compensates electric current, and electric current phase is compensated by by constant current and second
Subtract the 4th voltage signal by the use of capacitor generation as ramp signal.
20. control methods as claimed in claim 19, wherein, the resonance crest for being obtained sampling by a RC integrating circuit
The normal phase input end in control source first voltage control electric current source, and the second reference voltage is input into first voltage control electric current source
Inverting input generating the first compensation electric current.
21. control methods as claimed in claim 20, wherein, the resonance trough for being obtained sampling by the 2nd RC integrating circuit
The normal phase input end in control source second voltage control electric current source, and the 3rd reference voltage is input into second voltage control electric current source
Inverting input generating the second compensation electric current.
22. control methods as claimed in claim 19, wherein, by the resonance peak voltage that obtains and the 4th reference voltage of sampling
The first pulse signal is generated compared to relatively, first voltage signal is sampled using the first pulse signal, and by first voltage
Signal and the first voltage signal that obtains of sampling are separately input to the normal phase input end in tertiary voltage control electric current source and anti-phase defeated
Enter end to generate the first compensation electric current.
23. control methods as claimed in claim 20, wherein, the resonance peak voltage and the 5th reference voltage that sampling is obtained
The second pulse signal is generated compared to relatively, first voltage signal is sampled using the second pulse signal, and by first voltage
Signal and the first voltage signal that obtains of sampling are separately input to the normal phase input end of the 4th VCCS and anti-phase defeated
Enter end to generate the second compensation electric current.
24. control methods as claimed in claim 17, wherein, when the first control signal is high level, the 3rd control signal
It is low level, electromagnetic oven major loop is switched off；When the second control signal is high level, the 3rd control signal is high level,
Electromagnetic oven major loop switch conduction.
25. control methods as claimed in claim 17, wherein, methods described also includes：
Second voltage signal is sampled and sampled second voltage signal is exported as the first output voltage signal；
Obtain voltage corresponding with the voltage difference between second voltage signal and the first output voltage signal；
The voltage and second threshold voltage are compared with output protection control signal,
Wherein, the result and protection that the voltage of the voltage of the 4th voltage signal and tertiary voltage signal is compared acquisition are controlled
Signal carries out obtaining the first control signal after logic or computing；
Wherein, cycle of the sampled signal sampled to second voltage signal and control electromagnetic oven major loop switch conduction and break
The cycle phase of the 3rd control signal opened is same, and is sampled for the peak voltage to second voltage signal.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510114971.3A CN104850165B (en) | 2015-03-16 | 2015-03-16 | Control circuit, control method and its electromagnetic oven for electromagnetic oven |
| TW104115599A TWI558272B (en) | 2015-03-16 | 2015-05-15 | Induction Cooker and control circuit and control method |
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| CN201510114971.3A CN104850165B (en) | 2015-03-16 | 2015-03-16 | Control circuit, control method and its electromagnetic oven for electromagnetic oven |
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| CN104850165B true CN104850165B (en) | 2017-06-20 |
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| CN106507521B (en) * | 2015-09-07 | 2022-11-22 | 佛山市顺德区美的电热电器制造有限公司 | Overvoltage zero-crossing detection circuit of electromagnetic heating control system |
| CN106714354A (en) * | 2015-11-13 | 2017-05-24 | 比亚迪股份有限公司 | Electromagnetic heating device and control method thereof |
| CN105465847A (en) * | 2016-01-13 | 2016-04-06 | 昂宝电子（上海）有限公司 | Analog control system for electromagnetic oven and electromagnetic oven |
| TWI655880B (en) * | 2018-01-31 | 2019-04-01 | 盛群半導體股份有限公司 | Electromagnetic induction heating device and protection control circuit thereof |
| CN112839398B (en) * | 2019-11-25 | 2023-03-31 | 佛山市顺德区美的电热电器制造有限公司 | Electromagnetic heating device and dry burning detection method thereof |
| CN112105106B (en) * | 2020-08-14 | 2022-09-27 | 中山市合硕高品电器有限公司 | Control method and device of induction cooker |
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| KR100629334B1 (en) * | 2004-10-26 | 2006-09-29 | 엘지전자 주식회사 | Induction heating cooker to limit the power level when input voltage is low and its operating method therefor |
| TW200702968A (en) * | 2005-07-12 | 2007-01-16 | Holtek Semiconductor Inc | Architecture and method of power-controlling circuit applicable to electronic cooker |
| US7663352B2 (en) * | 2007-08-27 | 2010-02-16 | System General Corp. | Control circuit for measuring and regulating output current of CCM power converter |
| CN101500350B (en) * | 2008-01-30 | 2011-07-06 | 义隆电子股份有限公司 | Electromagnetic furnace control circuit and electromagnetic furnace using the same |
| CN101754506B (en) * | 2008-12-12 | 2013-03-20 | 深圳市鑫汇科科技有限公司 | Electromagnetic oven power automatic calibration method and circuit |
| CN102378425B (en) * | 2010-08-10 | 2015-07-29 | 深圳市爱可机器人技术有限公司 | A kind of electromagnetic oven and heating control circuit, automatic/semiautomatic cooking equipment |
| CN102281658A (en) * | 2011-07-25 | 2011-12-14 | 深圳和而泰智能控制股份有限公司 | Synchronous signal acquiring circuit and control device for induction cooker and induction cooker |
| US9312772B2 (en) * | 2013-01-16 | 2016-04-12 | Intersil Americas LLC | Current limiting scheme for a converter |
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| CN104850165A (en) | 2015-08-19 |
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